I have different showplus slideshows on different pages. If one doesn't work they all don't work. If one works they all work.
This phenomenon is most likely not specific to showplus but to particular versions of Joomla/MooTools or other extensions showplus is used in conjunction with; I am afraid it is not possible to give a simple "canned" suggestion that fits all cases. In general, it is best to contact the extension developer directly (see Support button), a review does not expose your e-mail to the listing owner and it is not possible to contact you for details. (As a bonus, you get a much faster reply by contacting the developer directly; it takes time before your review is approved and exposed to the listing owner, whereas an e-mail lands directly in the developer's mailbox.)